IPA: /ˈʌndəˌlaɪn/
KK: /ˈʌndərˌlaɪn/
A line drawn underneath a word or phrase to show that it is important or to emphasize it.
The teacher asked us to underline the key points in the text.
To draw a line beneath something, usually to highlight or emphasize it.
In her notes, she decided to underline the most important points.
Past: underlined
Past Participle: underlined
Underline → It is formed from "under-" (meaning beneath) and "line" (from Old English "līn", meaning a line or string). The word "underline" means to draw a line beneath text to emphasize it or indicate its importance.
Think of drawing a line "beneath" something to emphasize it — that's what underline means.